Doctor Who has been around in one form or another (or multiple forms at the same time) for over 40 years. Prior to 2010, there have been nine different Doctors, each with their own particular fan base, mythology, attitude, and outlook. Imagine then, if you can, the monumental task of introducing a new Doctor – the Eleventh Doctor. To do it right you not only would have to set the man apart from the others, you would have to manage to retain all that is the legend. With tales of the Doctor having been in existence for more than 40 years, there is a whole lot of history the Time Lord from Gallifrey carries.
Now consider that the most recent Doctor, the Tenth Doctor (portrayed by David Tennant), was massively popular and that although he wasn't the first Doctor of the reborn series, it is he who best embodies it. How do a new executive producer (Steven Moffat) and a new Doctor (Matt Smith) step in to the story, and not only leave open the potential to bring in new fans, but not alienate those who have become accustomed to former executive producer Russell T. Davies version of the series and Tennant's Doctor? It is a monumental task.
In speaking of becoming The Doctor, Smith, in the promotional material that accompanied the premiere episode of the new season, states, "I think these things are only as intimidating as you allow them to be." Perhaps either the 28-year-old man has, like the Time Lord he plays, truly seen everything, or maybe he's just wise beyond his years. What he is not is jaded, stating that "it's a real privilege to join such a successful show… it's good to be part of something strong and long may it continue."
If the season premiere, "The Eleventh Hour" is any indication, Smith and Moffat may have a very long – and very successful – run with Doctor Who. Is Smith young? Yes. Does he look young? Yes. Is it disconcerting? A little. However, Smith, Moffat, and everyone else involved have managed to work in enough similar mannerisms and attitude from the previous incarnations of The Doctor that even though things are new and different, the man on screen is unquestionably the Time Lord we have come to know, love, and sometimes even fear.
It would be hard to suggest that the Doctor we see in "The Eleventh Hour" is the final iteration of Smith's incarnation of the Time Lord. The Eleventh Doctor does find himself somewhat out of sorts in the episode, not quite sure what sort of food he likes, and still appearing somewhat uncomfortable in his own skin. That is a natural outgrowth of the Doctor being new to the body, but what we can glean from that is that both Smith and Moffat have a clear understanding of who the Doctor is. That is not surprising considering the cultural force Who is in England, and that Moffat grew up as a fan of the series. In fact, Moffat says "the reason I started working in TV is because I was such a huge fan of Doctor Who."